Starting with TCC v11, having two or more extra header specifications (/H) on the SENDMAIL command works incorrectly. The manual specifically allows multiple /H instances on the command. It acts as if an extra blank line were inserted into the outgoing message after each /H line; the received message has the first extra header specified with /H correctly in the headers, but then each additional extra header specified with /H shows up in the body of the message. Here's a simple .btm file: Code: sendmail /v ^ /h"X-Test-Header-1: Test header 1" ^ /h"X-Test-Header-2: Test header 2" ^ /h"X-Composed-Date: %_dow, %_day %@left[3,%_monthf] %_year %_time %@if[%_tzo gt 0,-,+]%@right[4,%@strip[":",%@maketime[%_tzo]]]" ^ %@option[mailaddress] "%@name[%_batchname]: Test extra headers" "Testing the effect of extra headers." (I've broken up the command for legibility, but it works the same way if it's all on one physical line.) This results in the following text being received as the text of the message: Code: X-Test-Header-2: Test header 2 X-Composed-Date: Sat, 6 Feb 2010 10:54:40 -0500 Testing the effect of extra headers. I've verified that it works this way through two different outbound SMTP servers, and retrieved with two different POP clients to eliminate the possibility that the problem is at one of my usual mail server sites. Also, it makes no difference whether the text of the body or the filename containing the body is specified (with @) . To work around this problem for now, I've replaced the command SENDMAIL with "C:\...\TCMD10\TCC.EXE /C SENDMAIL" . This aspect of the SENDMAIL command works correctly in TCC v10.